Mobile communication system has been developed to provide an audio service by securing user's activity and mobility. The ongoing trend of the mobile communication system is to extend its service capability to a data service as well as the audio service. Currently, the development of the mobile communication system enables a high-speed data service. Yet, since a currently serviced mobile communication system causes resource shortage and fails in meeting user's request for a faster service, the demand for a further advanced mobile communication system is rising.
One of the most significant requirements for the next generation wireless access system is the capability of supporting the high data rate requisite. To this end, many on going efforts are made to research and develop various technologies including MIMO (multiple input multiple output), CoMP (cooperative multiple point transmission), relay and the like.
In order for these technologies to obtain best performance, it may be difficult to use the same downlink control channels used by legacy systems. To settle this difficulty, an enhanced physical downlink control channel (e-PDCCH) is introduced into 3GPP LTE-A system to increase capacity of a physical downlink control channel (PDCCH) of the legacy 3GPP LTE system.